The function of a trend log is to log the variable that it is connected to and store the records.
To be able to store larger amount of records, it is possible to connect an extended trend log using EcoStruxure Building Operation. The records of the trend log and the extended trend log can be presented numerically in a trend log list. The records can also be processed by a calculation method before they are presented.
During the logging process, activity in the server may be temporarily increased. This is because a second polling rate is applied to each variable 30 seconds before the logging time. With multiple logs, the increase in activity can be significant. After 30 seconds, when a value is logged, the polling rate is set to the maximum integer.
You use a trend log to collect data and then store the records. A record contains a log value or an event as well as its time stamp and an optional comment. A trend log can log an analog variable, a digital variable, or an integer variable.
All trend log types can be configured to log meter consumption and handle meter replacement. Extended trend logs can be used to structure the log data and to store it where there is greater storage capacity.
The change of value trend log records the variable each time the difference between the current value and the last log value exceeds the delta. Use the change of value trend log to, for example, record a variable that has an unequal oscillation.
The interval trend log collects data at a specific time interval. Each logged value is stored as a record in the trend log. Use this trend log when the logging interval is less than 1 hour.
A log processing trend log enables calculation within or between various trend logs. With this feature, building managers can gather new information about how the building is operating, they can view historical data that is calculated against new data and in this way detect new trends, they can compare various values and calculate a new trend log displaying relativised behavior, or unify measurements made with different units. The results from these calculations can indicate anomalies that have other reasons than the naturally varying conditions, so that it becomes easier to find problems with the building.
The manual trend log records data that you manually enter. The manual trend log does not log a variable. Use this type of trend log when values from offline devices have to be manually registered to the trend log. For example, if you want to create a trend log that monitors an electricity meter that cannot be connected to the EcoStruxure BMS.
The variable triggered trend log records the variable when the conditions of the associated trigger variable are met. Use this type of trend log when the log interval is scheduled to log monthly or yearly, or when another device is used to trigger the log.
The implicit log is a change of value trend log which monitors the IO variable and records a new value if the variable exceeds the delta. Each log value is stored as a record in the trend log. The delta is automatically defined by the EcoStruxure Building Operation software depending on the measured unit of the device that is connected to the IO port.
The meter function adds meter properties to any trend log type to seamlessly handle consumption calculations independent of meter rollover or meter exchange.
All trend logs store records by using the circular storing principle; you can also connect trends logs to external trend logs with larger storing capacity. For some trend logs you can set up conditions that have to be fulfilled before the trend log starts recording.
All trend logs use circular storing. How many records a trend log can store before overwriting old ones depends on the trend log configuration.
The interval trend log and change of value trend log start recording values when the configured activation conditions are met. If an activation variable is used, both the activation variable and the activation time have to be true for the trend log to start recording.
You use an extended trend log to transfer records from a trend log. An extended trend log can be connected to a trend log or connected in a series to another extended trend log. Only one extended trend log can be connected to a trend log.
You can define the unit of a trend log when the trend log is created or on a previously created trend log where no unit has been set.
For example, a variable that represents a temperature in Kelvin is surveyed by an interval trend log. The trend log is configured to store the values in degrees Fahrenheit. A trend log list is connected to the trend log. If you display the trend log list on an operating system that uses the SI metric system, the values in the trend log list are converted and displayed in degrees Celsius.
The trend log list numerically displays the records of a trend log or an extended trend log. The records of the trend log can be processed by a calculation method before they are presented in the trend log list.
The trend log list can only display one trend log at a time and must be manually refreshed to display recently recorded values.